What Is This

[drf76]

Can anyone tell me where the Thermo amp is located, im trying to chase why ive lost my A/C input signal to the ecu, Ive tried using my standard ecu as im running a powerfc and ive also changed my A/C climate control module with no help, just following the wiring diagram and i cant find the thermo amp, im guessing the A/C amp is the module that you control the Heater and A/C but what is the thermo amp?? Any one got any ideas??